A curb is a border that forms an enclosing or dividing framework or part of a gutter along the edge of a street. Although curbing, especially concrete curbing, exhibits important structural and functional characteristics, its aesthetic appeal is now beginning to prove desirable in landscape architecture. With the availability of concrete dies and specially designed curb forming devices (also referred to “edging devices” or “edging machines”), concrete curbing can be extruded in a wide variety of colors and shapes.
Curb forming devices are machines that move forward by the action of a ram, driven by a motor, which pushes concrete from the base of a hopper into a mold that extends from the back of the machine. The mold has a cross-section that is generally the shape of an inverted U, in which the ends of the arms of the U are directed against the ground. The ram pushes against the concrete until the mould has been filled with it. Pressure on the ram when it continues to push against the concrete drives the edging machine forward.
A typical curb forming apparatus has two forwardly mounted wheels. The wheels rotate on their axles or hubs, supported on respective wheel forks, which are at the lower ends of respective tubular, telescopic wheel supports. The wheel supports are mounted toward each end of a wheel support plate, which is connected to the motor housing of the machine. The tubular, telescopic arrangement enables the distance of each wheel from the wheel support plate to be adjusted (for example, when the machine is used to lay edging strips across sloping ground).
A short bar or “fork bar” is attached to and extends forwardly from each fork. The fork bars have short bolts on their tops. The two ends of a steering rod fit over the short bolts, so that when one fork bar is moved, the other fork bar moves by the same amount. A steering lever is connected to one of the fork bars, which extends further from the top of its associated fork than the other fork bar.
This edging machine has generally functioned well. However, when the garden or other region in which edging strips are being laid is not level, the wheels of the edging machine have to be set at different heights to ensure that the wheel support plate is substantially horizontal. This means that the steering rod, which is connected to the two fork bars, cannot be horizontal. A consequence of this is a net toe-in of the wheels. Under these conditions, it is difficult for an operator of the edging machine control the steering of the machine.
In view of these and other deficiencies in the art, the continued need for new and useful improvements is evident.